Removable tab having a protective coating



y 5, 1970 P. H. HELLER 3,510,022

REMOVABLE TAB HAVING A PROTECTIVE COATING Filed not. 17, 1968 INVENTOR.Q04 A1 #5415? United States Patent 3,510,022 REMOVABLE TAB HAVING APROTECTIVE COATING Paul H. Heller, 2210 New Haven Ave., Far Rockaway,N.Y. 11691 Filed Oct. 17, 1968, Ser. No. 768,513 Int. Cl. B65d 17/24 US.Cl. 220-54 7 Claims ABSTRACT OF THE DISCLOSURE This disclosure isdirected to a metal can, such as for beverages, of the type which has aremovable metal tab scored in the top thereof. The improvement residesin partially coating the top and tab portion of the can with plastic.Upon removal of the tab member the plastic coating remains and preventsinjury to the user from sharp metal edges at the point of former joinderof the tab and the top of the can.

Background Metal cans are widely used for beverages such as beer andsoda. Several years ago cans having removable pulltabs were introducedand readily accepted by the public. The tops of these cans are scored toform a key-hole shaped tab to which a ring or tongue is attached. Uponpulling the ring or tongue the tab is lifted off the top of the canleaving a key-hole shaped opening from which the beverage may be pouredor removed. Unfortunately due to the metal stamping or scoring to formthe tab and the step of pulling off the tab, very sharp edges are lefton the top of the can. These sharp edges pose a particular danger toconsumers when drinking directly from the cans by pressing their lipsagainst the key-hole shaped opening. The dangers have of course provengreatest for young children who might be inclined to place their lips,tongues, or fingers against these edges. A further drawback of this typeof can is its greater tendency to lose carbonation through minute leakscaused by the scoring around the tab.

It is therefore an object of the present invention to provide for animproved can having a readily removable tab portion.

It is a further object of this invention to provide for such a can whichcan be more safely used by the consuming public.

Yet another object is to make such a can which will less readily losecarbonation.

These and other objects of the present invention may be met by providinga protective coating on the top of the metal cans as set forth in thefollowing detailed description.

The invention This invention is directed to an improved metal can of thetype having a removable member, such as a tab scored into the top of thecan. A plastic film is provided on the top of the can; the film remainsafter opening of the can and covers the exposed metal edges left in thetop of the can after removal of the tab.

FIG. 1 shows the top of a can with a plastic coating partially on andaround the tab portion of the can.

FIG. 2 shows the can of FIG. 1 with the tab portion of the can removed.

The lid or top 1 of the can has a generally key-shaped removable tabportion 2, as defined by the score-line 3. In about the middle of thecan a handle 4 is afiixed to the tab. This type of can is well-known andof conventional construction. The improvement of this invention residesin a plastic coating 5 which covers a portion of the lid and slightlyoverlaps the score-line to cover a small 3,510,022 Patented May 5, 1970part of the tab. A transparent coating is shown to reveal the score-lineunderneath, for ease in depicting the construction of the can.

Upon removal of the tab by means of the handle, an opening 2' is formedas defined by the score-line edge (FIG. 2). The plastic coating 5remains attached to the lid and the edge 6 of the plastic coatingprovides protection for the user of the can from the sharp edge at thescore-line formed by removal of the tab.

The coating of the present invention is applied along the scoring whichoutlines the removable tab. A minor portion of the coating overlaps thescoring and is aflixed to the removable metal tab. The majority of thecoating is firmly anchored to the top of the metal can, contiguous tothe tab portion. Since the coating is coherent, and somewhat flexible,upon removal of the tab the minor portion of the coating separates fromthe tab and the entire coating remains on the top of the can. Theaforementioned minor portion of the coating, after removal of the tab,overlaps the key-shaped hole and provides protection from the sharpmetal edges. By the use of a strongly adhering coating, in the above,additional protection is provided against loss of carbonation at thescored part of the can.

Metal packages and containers are made out of steel, tin and aluminum.The most common of these is the tin can, which contains only a smallportion of tin, used for the coating of the steel sheet. In the field ofbeverages, aluminum has now come to the fore as a packaging material.The present invention is directed to metal cans made of any of thesematerials which have removable portions formed therein by scoring orstamping or any similar operation whereby removal of the intendedportion leaves sharp metal edges.

Many different types of coatings may be used on metal cans to provideprotection against these sharp metal edges. These coatings shouldreadily adhere to the metal cans and preferably be capable ofapplication during the can forming process. The coatings should be toughso that they are not torn during removal of the tab from the can. Thecoatings should be flexible so that they present a soft plastic edgeoverhanging the opening in a can after removal of the tab. Theseproperties are present in numerous commercially available coatings inthe food or beverage industries.

The coatings may be applied to the can in several different ways. Forexample, the coatings can be applied directly during the forming orstamping operation from reservoir fed devices. The coatings may bepainted onto the cans by brushes or other types of applicators.Alternatively the coating may be sprayed onto the can, orelectrodeposited, or powder-pressed. Combinations of these steps may beused, in conjunction with heat and pressure sealing operations. Themethod of applying the coating is tailored for the particular plastic orcombination of plastics which are to be used.

The important factor in choosing and applying the coating is that theminor portion of the coating should be capable of being stripped fromthe tab during removal of the tab from the can, and yet this minorportion should remain coherent with the remainder of the coating whichremains firmly adhered to the can and which surrounds the hole formed byremoval of the tab. For example the coating may be wide, wherein A ofplastic is on the tab and is on the top of the can adjoining andsurrounding the tab. Upon removal of the tab the & wide coating on thetab is stripped therefrom since it is coherent with the wide coatingfirmly adhered to the remainder of the can. The wide plastic striptherefore overhangs the opening in the can and protects the consumerfrom the sharp metal edges left after removal of the tab. The dimensionsjust set forth are of course only illustrative and may be "variedwidely. It is preferable that the amount of coating which is placed onthe metal tab be maintained at a minimum so that it may readily bestripped therefrom and yet will not obstruct the opening in the can. Theamount of plastic or coating which surrounds the tab should be severaltimes the amount which is on the tab itself so that the entire coatingis not pulley ofl during removal of the tab. Alternatively this portionof the coating which surrounds the tab may be specially treated, by heator pressure, to provide permanent adhesion to the metal can whereas thecoating on the tab itself remains strippable.

Among the plastic coatings which may be used in the present inventionare the polyvinyl acetals. Polyvinyl formal may be used as an enamel.The enamel is prepared from the formal in combination with an alkylphenolic resin in a solvent mixture of cresylic acid or furfural andnaphtha. Properties making the formal valuable in this applicationinclude toughness, adhesion, flexibility, and resistance to heat,abrasion, solvents and oils. Granular polyvinyl formal may be used onsurfaces coated with a liquid phenol-formaldehyde resin afterapplication of heat and pressure. Emulsions may also be prepared forbonding to metals such as aluminum. These polyvinyl formals mixed withphenolics, and their method of application, are well-known as food-canlinings, and the technology therefrom can be adapted for the presentinvention.

Plasticized polyvinyl butyral, cured or cross-linked with aurea-formaldehyde, phenol-formaldehyde, or other resin, provides aflexible waterproof coating. A wash primer type of metal conditionerwith polyvinyl butyral has excellent adhesion to clean metal surfacesand airdries rapidly to leave a uniform protective film. A butyral washprimer under a topcoat of polyvinyl chloride-acetate copolymer alsoprovides corrosion resistance to metal surfaces. Thus the butyralcoating may be used to improve the adhesion of other plastics toaluminum. Butyral solutions readily form cast films which are waterproofand very flexible. A small amount of phenolic around the edges of such afilm will cement to almost any metal surface under heat and lightpressure.

In applying coatings as powders, the pulverized material is brought incontact with the can and then fused by heat into a solid film. Amongwell-known polymer powders, which may also be available in solvents, arecellulose-acetate-butyrate, chlorinated polyether, fluorocarbon resins,polyesters, polyethylene, polyvinylchloride and epoxy resins. Byselection of the powder, plasticizer, and sometimes primer, protectiveand esthetic coating can be produced. The coating can be tough,flexible, permanent or strippable, and can have a pleasant feel, lusterand attractive appearance. In addition, with electrostatic powderapplication methods, selected areas can be coated and automation of thecoating operation is greatly simplified.

Particularly strong bonds may be obtained with epoxybased resins whichare commercially available for adhesion to metals such as aluminum.These resins may be cured at room temperatures or at elevatedtemperatures and pressures. These resins may perform the added functionof a seal when added over the scoring which forms the tab member on thetop of a can. This sealing function prevents the loss of carbonationwhich might otherwise occur due to a faulty scoring or stampingoperation. The epoxy-based resin may also be used as a priming layerover which a softer plastic, such as a rubber cement, may be used. Itwould be the rubber cement edge which therefore hangs over the openingin the can and provides protection to the consumer.

Modifications can be made in the preferred embodiments of the inventiondescribed above without departing from the scope of the inventiondefined by the appended claims.

I claim:

1. In a metal can for liquids having a preformed removable tab portionformed in its lid, the improvement which comprises a coherent plasticcoating on the adjoining areas of said lid and a portion of said tab,said coating extending from said lid to a limited area of said tab onits periphery and said plastic adapted to adhere to said lid uponremoval of said tab wherein a minor portion of said plastic coating ison the periphery of said tab and the remainder of the plastic coating ison the lid of said can substantially around the tab, wherein uponremoval of said tab the plastic coating overhangs the opening formed insaid can but does not substantially obstruct removal of liquidtherefrom.

2. The metal can of claim 1 wherein said plastic coating comprises anepoxy-based resin securely adhered to said can.

3. The metal can of claim 1 wherein said plastic coating comprises arubber-base resin securely adhered to said can.

4. The metal can of claim 1 wherein said minor part of said plasticcoating is strippably adhered to said removable tab portion and saidremainder of said plastic coating is permanently adhered to the area ofsaid can adjoining the removable portion.

5. The metal can of claim 4 wherein said remainder of said plasticcoating includes an epoxy-based resin and said minor part of saidplastic coating is a rubber-based resin.

6. The can of claim 1 wherein said tab is defined by a scoreline on saidlid and said plastic coating is a strip of plastic over said score-line,with the majority of said plastic on said lid and the remainder on saidtab.

7. In a metal can for liquids having a preformed removable tab portionformed in its lid, said tab portion being defined by a score-line onsaid lid, the improvement which comprises a strip of plastic coatingover said score-line, a first portion of said plastic being on theperiphery of said tab and the remainder of said plastic being on the lidof said can substantially around the tab, and said remainder of saidplastic being permanently adhered to the lid of said can wherein uponremoval of said tab the first portion of said plastic overhangs theopening formed in said can but does not substantially obstruct removalof liquid therefrom.

References Cited UNITED STATES PATENTS 3,204,805 9/1965 May 220-24GEORGE T. HALL, Primary Examiner U.S. Cl. X.R. 22090.6

